Switch and enclosure therefor



April 3, 1962 A. R. NORDEN SWITCH AND ENcLosURE THEREFOR 3 Sheets-Sheet 1 Filed Feb. 19, 1959 ATTORNEY April 3, 1962 Filed Feb. 19, 1959 FlG. 3

A. R. NORDEN SWITCH AND ENCLOSURE THEREFOR Sheets-Sheet 2 ATTORNEY April 3, 1962 A. R. NORDEN 3,028,459

SWITCH AND ENcLosURE THEREFOR Filed Feb. 19, 1959 5 sheets-sheet s INVENTOR. ALEXANDER R. NORDEN BY @d EMMA;

ATTORNEY United States Patent 3,028,459 SWITCH AND ENCLOSURE THEREFOR Alexander R. Norden, New York, N.Y., assignor to Federal Paciiic Electric'Company, a corporation of Delaware Filed Feb. 19, 1959, Ser. No. 794,316 13 Claims. (Cl. 200-50) This invention relates generally to a switching device such asa switch or a circuit breaker and enclosure therefor and, more particularly, to the front operated type of switching device. y

One important object of the present invention is the provision of a novel front operated switching device which is reversibly positionable with respect to a panel or enclosure in such manner that the actuating handle .which has an oit-center pivot may be oriented with the handle extending from the pivot in generally the same common direction independent of the selected position of the switching device; Pursuant to this object of the present invention the actuating handle is pivotally mounted on a cover part to swing across the face of the cover and is provided with a separable operative connection with the switch mechanism mounted on a basepart, the operative f connection being so symmetrically disposed as to permit the reversal of the basefpart with respect to the cover part. The handle swings through a relatively narrow angle so that it extends in the same general direction from its pivot that islocated off-center of the cover. Accordingly for a given handle orientation the switchmechanism may be selectively disposed in bodily reversed positions. In the embodiment of the invention to be described hereinafter, a double branch switch enclosure is provided having similar switches in which one switch is reversed with respect to the other with the front operated actuating, handles being yoriented in a common direction.

Another important object of the present invention is the provision of a switch and enclosure therefor having a novel and improved interlock for the enclosure cover and the actuating handle of the switch. Pursuant to this object of the present invention, the enclosure is provided with an openable cover having an interlock controlled by the switch mechanism so that the interlock is eiective to latch the cover closed in the on position of the switch and to release the cover to permit the same to be opened in the off position of the switch. As a further feature the interlock is defeatable in a novel and improved manner to permit the cover to be opened in the on position of the switch. The interlock is coupled to the actuating handle through the over-centering spring means of the switch mechanism whereby the interlock is controlled by the position of the contacts. In this manner the interlock cannot release the cover for opening movement unless the contacts are open. In the event the interlock is frozen in the interlocked position, the switch may nevertheless be thrown to the oipositionto open the contacts whereby the interlock does not override contact opening. Further pursuant to this object of the present invention, the interlock for the actuating handle is responsive to the V'position of the enclosure cover so that on the opening of the lattera blocking action comes into play to prevent the actuation of the handle, the blocking action being defeated on theclosing of the cover.

Yet another object of the present invention. is the provision of a switch or circuit breaker and enclosure thereforof generallyimproved design and construction, and which are eminently suitable for the accomplishment of their intended purposes.

The above and other objects, features and advantages of the present invention will be more fully understood from the following description considered in `connection with the accompanying illustrative drawings.

3,028,459 Patented Apr. 3, 1962 In the drawings:

FIG. 1 is a front view of a double branch switch enclosure formed according to the present invention with both switches in an on or circuit closed condition and with the enclosure covers closed;

wFlG. 2 is a side elevational view thereof with a schematic partial showing of the switch mechanism of one switch with the other switch and enclosure thereat being partially broken away to reveal structural details of the switch; f

FIG. 3 is ka fragmentary side elevational view showing the cover interlock and associated switch mechanism, the solid line position of the parts corresponding to the on position of the switch and the dotted line position corresponding to the oit position of the switch;

FIG. 4 is av sectional view taken on the line 4 4 of FIG. 3; v

FIG. 5 is a side elevational view of the switch with portions broken away to reveal structural details of the handle and handle interlock, the switch being shown mounted in the enclosure with the cover thereof removed;

FIG. 6 is a view similar to FIG. 5 showing the enclosure cover in the closed position;

FIG. 7 is a partial perspective view illustrating the manner of interlocking the cover and base parts of the switch;

FIG. 8 is a plan cross-sectional view of the apparatus in FIG. 5 along the line 8 8 therein.

, Referring to the drawings, and more particularly to FIGS. l and 2 thereof, there is shown a double branch enclosure 10 having switches 12 and 12 secured therein, the switches being of identical construction but reversibly disposed as will be described in detail below. The enclosure 10 is preferably of sheet metal construction and comprises arecetacle part 14 having openable covers 16 hinged to opposite ends thereof as indicated at 18. The covers 16 are individually movable between open and closed positions and in their closed positions their inner edges 20 are disposed in closely adjacent relation at the longitudinal center of the enclosure. The receptacle part 14 comprises opposite sidewalls 22 and 24, end walls 26 and 28, and a bottom wall 30 having a pan 32 secured thereto, said pan dening a mounting platform for the switches. yThe covers 16 are suitably hinged to the end walls 26 and 28, and the confronting edges 20 of said covers have inturned flanges 20. The covers 16 have openings 34 which register with the switch cover blocks 36 for exposing the latter in the closed position of the covers 16.

The switches 12, 12 are of basically conventional construction, departing from conventional construction in the respects to be described in detail below. Each switch comprises interiitting detachably secured cover and base parts 36 and 38, respectively which house the switch mechanism 40, the Vpart 38 being suitably secured to the bottom pan 32. The parts 36 and 38 are preferably molded of a suitable insulating material. The switch in-` cludes the usual terminals 42 which are adapted for connection into a circuit to be controlled. The switch is of the three pole type, each being provided with an associated pair of stationary and movable contacts 44 and 46, respectively, the movable contacts being vmounted on movable contact members 48 which in turn are mounted for actuation by the bar 50 which has an axis of rotation extending longitudinally of the switch. Thus the bar 50 provides for the simultaneous actuation of the movable contact members of the three poles. The contact members 48 are movable to open and ,closed positions by the operating mechanism indicated'generally at 52, which is provided with overcentering spring mechanism. The switch is of the quick make and break type and operatively associated with mechanismSZ are the over-.1

centering springs 54. The mechanism`52 is thus of the quick make and break type and includes an operating member 56 having a projecting pin 58 which is pivotally movable in a path disposed transversely of the switch to actuate the movable contact members 48.

Pursuant to the Y present invention, the pin 58, which provides a separable operating connection with handle 60, is disposed for movement along a path coincident with a transverse median line of the switch cover part and the extreme on and off positions thereof are equidistant from the center of the switch cover part and equidistant from the center of such median line. Diierently expressed, the intermediate point of the path oftransverse movement of the pin 58 is coincident with the center of the switch cover part which is at the intersection of the longitudinal and transverse axes thereof, this arrangement providing for the reversibility of the cover and base parts of the switch with respect to each other. The handle 60 is of the front mounted twist type and is suitably secured to the operating arm 61 which is journalled to rotation on the front wall 62 (see FIG. 5) of the cover block 36,y the operating arm being mounted on the underside of said wall. 'Ihe operating arm terminates in a forked fitting 64 which denes slot 66, the latter detachably receiving the pin 58 of the switch to form an operative connection therewith. The handle 60 is pivotally movable between on and oit positions, which are equidistant from the center of the switch cover,

to concomitantly actuate pin 58 along a transverse mediantive switches, the handles being symmetrically positionedV onv the enclosure and extending/in a` downward direction, the operativey connections 58, 66 of switch 12 being oppositeto the corresponding connections of switch 12. It

will be understood that the base and cover parts of thel breaker may be` secured in interitting relation in bothV relative dispositions as exemplified by switches 12 and l12.

there is provided a cutout and projection 63 and 65, respectively which are formed complementary to the projections 67 and edge portions 69, respectively at the topf of the base part 38 for interlocking the base and cover parts of the switch in either relative disposition as describedabove. Thus both/ends of both the cover and base parts are similarly symmetrically formed so that the cover partmay be secured' to the base part in interlocking. relation therewith in the selected relative disposition. Asymmetrically positioned along the longitudinal axis of the cover part is a projecting fitting 71 which defines an aperture 73 for the screw 75 which seats on the shoulder 77 delined by the counterbore 79 which is open to the front of the cover part, the screw 75 being received in aregistering threaded fitting 81 or 81 of the base for securing the base and cover parts in assembled relation. In one relative disposition of the cover and base parts, the screw 75 is received in fitting 81' as shown in FIG. 5 and in the opposite relative disposition the screw 75 will be received in registeringlitting 81 for securing the parts in assembled relation.

It will be observed that the base part projects laterally beyondy the coverpart to enclose the switch mechanism. The aforedescribed `interlocking connection between the cover and base parts of the switch provides for the absorption of'` the torque of the handle 60 by the entire casing`A of the switch which forms a rigid unitary structureinlthe assembled relation of the cover andbase- More particularly, as' shown in FIG. 7, at eachr corner portion of lthev bottom edge of the cover part 36l 4y s v parts. The handle 60 is carried by the switch casing itself and not by the enclosure cover to thereby eliminate alignment problems in providing a separable connection between the switch and cover carried handle and the attendant lnecessary cover reinforcement to absorb the torque of the twist operating handle.

The actuating handle 60 is pivoted at one end with' the" pivot axis being disposed off-center of the cover part, that is along the-longitudinal axis of the cover part but spaced from the transverse axis thereof, the actuating handle swinging through a relatively narrow angleY across the face of the cover part.- More particularly, the actuating handle pivotally moves within the confines of opening 34, the handle clearing the cover 16V at saidk opening.y Thus the actuating handle with its off-center pivot may be oriented with the handle extending from the pivot in generally the same common direction independent of the selected position ofV the reversibly positionable switching device. The pivotal axis of the handle 60 is disposed perpendicular to the cover 16 in the closed position thereof.

With reference to FIGS. 5 and 6, the handle 60 com prises a hub 68 which is secured to the arm 61, the handle being hollowed out and open at the rear. The handle is provided with a series of three apertures 70 which are dimensionedl to receive the shank of the padlock, the, handle having a longitudinally reciprocable flat-locking slide 72 `provided with apertures 74 which register with apertures 70 in the locking position-of the slide for externally locking the operating handle by one or more;

padlocks.v

Secured to the face of the cover block is a` metal platek 82 which is provided with a suitable opening for theextension therethrough of -the arm 61.

The plate 82 is provided with a longitudinal slot 84V which communicates with the slot 86 extending into the cover part 36, the slot 86 having acircular closed bottomrecess 88 in which a compression spring 90 is seated.

The plate 82 is also provided with an aperture S3 in registry with counterbore 79 for the reception ofA screw 75. Axially movable in slot 86 is a handle interlock-mem- Iber 92 which is constituted by'a ilat plate'having a handle blocking part 94 and a cover actuator part 96 in longitudinally spaced relation, the part 94 extending through slot 84 of plate 82. The portion 98 of the member 92 seats against the bottom portion of the plate 8210 limit the extension of the member 92 outwardly of the-V cover block. The member 92 has a depending part- 102` which extends into the spring 90, the latter serving to biasl the member 92 to its extended handle blocking position shown in FIG. 5. The spring '90 seats against the bottom of recess 88 at one end and seats against the edge 104 of member 92 at the opposite end. In the extended handle blocking position of member 92, which position the latter" assumes with the companion cover 16 open, the part 94` is dispiosed'in the path of movement ofthe handleto thereby block the movement thereof out of position. With reference to FIG. 6, on closing the cover, the latter depresses the part Y96 inwardly of the cover block to thereby concomitantly retract the part '94' out of the path of cover latch is provided forv each of the covers 16, the

interlock being controlled by the switch mechanism so as to be effective to latch the cover closed in the on posi` tion of the switch and to release the cover to permit the same to be opened in the oi position of the switch. The interlock for each cover 16 comprises an interlock member 106 (FIG: 3) pivotallym'ounted on a companion` sidewall 22, 24 of the enclosure by means of the pivot pin 108, the member 106 being operatively associated with a catch 110. I'he catch is constituted by a U-shaped part having laterally spaced differential length legs y112 and 114 which are interconnected by a base portion 116, the longer leg 114 being suitably secured to the inside face of the cover with the shorterleg 112 defining a latch portion which is disposed to interlock with a companion latch portion 118 of the member 106. The member 106 is preferably of stamped integral metallic construction and comprises a base part 120 and laterally offset parts 122 and 124, the part 122 Vhaving a V notch y126 at the top thereof defined by the shoulders or cam edges 128 and 130. The part 124 defines a longitudinal slot 132 (FIG. 4) extending transversely of member 106 and depending from part 124 in the plane of part 120 are portions .134 and 134 which are spaced from eachother to define a notch 136 therebetween. `The portions 134 and 134' have shoulders 138 and 138', lrespectively which are coincident with the top edges thereof and which` coact with the auxiliary lever 140, the latter being preferably of stamped metallic construction. The lever 140 comprises coplanar longitudinal straight portions 142 and 144 and an intermediate inclined portion 146, the portion 142 being normallyv seated against the shoulders 138 and 138 and between the part 124 and the enclosure sidewall in slot 132. The portion 142 has a depending coplanar portion 148 which extends in notch 136 in substantially flush relation with portions 134 and 134', the portion 148 having a laterally offset terminal part 150. The interlock spring 152y has one end interengaged with the pin 154, which is secured to the enclosure sidewall, and its opposite end is engaged in the aperture 156`ofpart 150. The spring 152 is elective to bias the member 106 and the lever 140 in a counterclockwise latching direction viewing FIG. 3, and` in normal operation the member 106 and lever 140 operate conjointly as a unitary assembly. r

The portion 144 has a laterally projecting flange 158 g` which is adapted to cooperatev with the interlock lever 160 and is disposed in the path of movement thereof. The lever 160 has a quadrilateral opening 162 for the reception of the bar 50 which actuates said lever. Laterally projecting from the lever 160 is a cam part 164 which engages. flange 158 to conjointly rotate the member 106 and lever 140 ina clockwise direction viewing FIG. 3 and disengage the latchportion 118 from catch 110, on the actuation ofthe switch to olf position. In the on position of the switch, the parts shown in FIG. 3- are in the solid line position with cam part 164 being spacedl from flange 158 and the member 106 being Abiased into interlock with the catch 110 so that the cover is latched closed due to the interengagement of latch portions 112 and 118. In the off position of the switch, the partsl` are in the 'dotted line position and the cam part 164 has been rotated by the bar 50 to correspondingly actuate member 1,06 andlever 140 against the bias of spring 152 and thereby release the latch portions 112 and 118` from interengagement and condition` the Vcover for opening movement.

Each'cover can be conditioned for opening movement inthe onv position'of the switch by defeating the interlock 106. The confronting edges 20 of the covers in the region of the interlocks have defined therebetween slots 166 saidV edges having turned down anges 168 thereat.

A tool T, such as a screwdriver, maybe inserted in a; 65

slot 166 as shown in FIG. 3 and depressed against the inclined cam edge 130 to pivot interlock-'V106 in an unlatching direction to the dotted line position to clear catch 110..

It will b elunderstoodv that on the withdrawal of the tool from the slot, the interlock will be spring returnedto thel line interlocked position for any reason, the switch mayV `blocking the opening movement of the covers.

24. The latch 170 is slotted asindicated at 178 for the reception of the stop pin 180 which is fixed to bracket 174, the pin 180 coacting with said slot to limit the extent of pivotal movement of the latch. The latch is provided with a torsion spring 182 to bias the same in a latching direction. In the latch closed condition of the cover, the shoulder 184 of the latch 170 is interengaged with the portion 186 of the cover to thereby prevent the cover from being opened, the latch 170 being pivotally movable in the direction of the arrow against the bias of spring 182 to disengage the latch from the cover to condition the latter for opening movement. n The covers may be externally locked by passing padlocks through the apertures 138 of the latches, the padlocks thereby From the aboveit will be apparent that both the switch controlled interlock 106 and cover latch 170 must be released to condition the cover for opening movement. In the off position of the switch, the interlock 106 will be released so that the manipulation of the cover latch to released position will condition the cover for opening movement, the cover being spring projected to open position under 'the action of spring biased member 92.

In the event the interlock 106 is frozen in the solid nevertheless be thrown to the off position pursuant to the instant construction. of the cam part 164 will pivotally lift lever 140 about shoulder 138' to position'140 against the action of spring 152, there being provided sufficient clearance in slot 132 to permit this movement of lever 140 relative to interlock 106. Thus in normal operation member 106 and lever 140 operate conjointly as a unitary assembly and in the event of a frozen interlock the switch may be thrown off by the movement of lever 140 relative to member 106,' as illustrated in FIG. 3.

c r1`he interlock lever 160 is conveniently formed as an integrally molded part. The lever 160 and consequently the cover interlock is controlled by the position of theinterlock through the overcentering springs 54. Thus the cover interlock cannot release the cover for opening movement unless the contacts open. If the contacts should weld or otherwise be stuck closed, the handle may be moved to the off position through the springs 54 but the cover interlock will not release. Thus the handleV gives a true indication of switch condition at all times pursuant to the present construction. As aforenoted, in the event the interlock member 106 is frozen l in the interlocked position, the switch may nevertheless be thrown olf to open the contacts.

Slide 72 was described as a locking slide. It achieves this purpose by virtue of structural detail in FIGS. 5 and 8. Locking slide has a downward projection 72a suitably received in a slot in forked operating arm 61 of molded insulation, and the slide is biased to the horizontally projected position shown by compression spring 190 received in slot 192 in slide 72, spring 190 pressing againstr inside shoulder portions 194 of the handle.

Slide 72 can be manually pushed to the left in FIG. 5 so that holes 74 line up with notches 74 for receiving one or more padlocks. This can be done only when the handle is in either the on or the off positions, for only then can slide portion 72a enter one of the slots 196 in plate 82. So long as padlocks arrest slide 72, portion 72a remains in one of the slots 196 and prevents handle operation. When the slide is freed by removal of all padlocks from the handle, spring 190 restores the locking slide to its projected position. l

So long as the handle is locked, accidental operation ofthe handle is impossible. If the handle is not locked, its slide 72 projects so that, when the cover is open unintentional operation `of the switch, as from off to on is blocked by projecting interlock 92.' However,

In such event the actuation it may be desirable to defeat this interlock as for test purposes. Inv that event, by deliberately depressing interlock 92, the service man can free the handle for switch operation.

Molded insulating arm 62 swings'inside cover 36 and in its end positions it engages the inside walls of the cover so as to confine the handle within the opening 34 of the cover. Projection 198 of arm 61 works within cut-out 200 in plate 82 (FIG. 8) to further insure limiting the sweep of the handle. Screws 202 join the handle 60 to arm 61, which function as a unit and are thus pivotally assembled to cover 36-82.

A safety feature isincluded in the apparatus, shown in FIGS. l and 6, for insuring the operating handle against becoming an electrical hazard to personnel. Handle 60 fof the metal is well insulated from all possible connection to the internal switch parts. However to eliminate electrical hazard, handle 60 and metal plate 82 are both electrically connected to each other by compression springs 208, and an electrical path from these is cornpleted via rivet 204 (four of which hold plate 82 to cover 36) and spring 206 in a groove in cover plate 36, to bear against interlock memberr92 which, in` turn, touches thev inside surface of the metal door of the grounded enclosure. Y y Y Various additional modifications ofv the above embodiments of the invention will readily occur to thoseskilled in the art, and therefore the invention. should be broadly construed in accordance with itsvfull spirit and scope.

`Having thus described my invention what I claim as new and desire to secure by Letters Patent is: c

l. A switching device, comprising base and cover parts interlockably engageable along their meeting edges for securement to each other in either of two mutually reversed casing defining relationships, said cover having a center point that occupies the same position relative to said base for both said reversed relationships, said base part having circuit controlling mechanism, said cover having an elongated external handle movable between on and ofi positions for correspondingly actuating saidl mechanism and said handle being pivoted to said' cover part near one end thereof and extending generally.

in the same direction in both said on and olf positions, and means providing an operative connection between said handle and said mechanism, said last named means including a pin carried by said circuit controlling mechanism and an arm xed to said handle and having a slot that meshes with said pin when said base and cover are engaged in either of said relationships, said pin having apath of movement whose center substantially coincides with the aforementioned center pointV of said cover, and the path of said pin from the center' of its path of travel to either extreme being short relative to the distance between the pivotal axis of said handle and said ycenter point of said cover.

2. Enclosed switching apparatus, including an enclosure having a door covering the front thereof, a switching device within the enclosure including a contact member movable between on and oi positions, a front operated handle movable about an axis perpendicular to the door when closed to operate the switching device, said door having an opening that is fully occupied by the switching device when the door is Vclosed and the handle being disposed forward of the door to constitute a front operated switching device, fa cover catch and a latch within th'e enclosure coacting with said cover latch when the handle has operated said contact member to its on position, and a yieldable drive connection from said Contact member to said latch normally operable .in the event of the cover catch beingnjammedr 3. Enclosed' switching apparatus, including Ian enclosure having a door covering `the front thereoffa switchp ing device within the enclosure including a vcontact member movable between on and oil positions, and op-Y eratingv mechanism therefor comprising over-centeringA spring means, a front operated handle movable about anV axis perpendicular to the door when closed to operate` said contact member through the intermediation of said over-centering spring means, said door having an opening that is fully occupied bythe switching devicewhen the door is closed and the handle being disposed forward of the door to constitute a front operated switching device, a cover catch and a latch within the enclosure coacting with said cover catch when the handle has operated saidv contact member to its on position, and a yieldable drive connection from said contact member to said latch normally operable to releasel the door catch when the handle-is operated to operate the contact mem'- ber to theV off position, the drive connection yielding to allow opening ofthe switching device intresponse to opening operation of thehandle in the event of the cover l catch lbeing jammed.` V

A 4. Enclosed switching apparatus, including an enclosure having a door covering the frontV thereof, a switching device within the enclosure including a contact member` movable between on and offpositions, and operating mechanism therefore comprisingv over-centering spring means, a front operated handle movable about an axis perpendicular to the door when closed to operate said contactme'mber throughrthe intermediation-of said overcentering spring means, said door having an opening that is fully occupied -by the switching device 4when theV doorY is closed and the handle being disposed forward of the door constitute a yfront operated switching device,

a cover catch and a latch within the enclosure coactingA with said cover latch when the handle has operatedsaid contact member to its on position, and a drive connection from said contact member to said latch operable to release the door catch when the handle is operated to operate the contact member to the olf position.

5. Enclosed switchingapparatus, comprising la switchA unit including a contact member movable between on and olf positions, `andquick make and break operating mechanism therefor comprising over-centering springmeans, andA a front operated actuating handle pivotally movable between on and oft positions to operate;

said contact member through the intermediation of said` over-centering spring means, a casing in which said unit is mounted',y an-openable cover for said casing, and interlocking means for said cover comprising releasably inter engageable latch parts carried by said casing and cover, respectively, said casing latch part beingoperativelyl associated with said handle through said over-centering spring means and normally responsive to the movement thereof whereby in the on position thereof said latchparts are interengaged to latch said cover closed, the pivotal movement of said` handle to said olf position being effective to concomitantly open said contact member and release said latch parts to condition saidw cover for opening movement, said handle being pivotally movable to o position through said over-centering spring' and pivotally movable to on and off positions for correspondingly :actuating said contact member through said over-centering spring means, and interlocking means for said cover comprising a stationary latch part carried by said cover, and a pivotally movable interlocking member carried by said casing. and releasably engageable ,withV said latch part for latching said cover closed, said unit having a part coupled with said contact member for conjoint movement therewith and normally responsive to the movement of said handle, said part being out of engagement with said interlocking member in the on position of said handle to interlock said member with said latch part, said part being normally pivotally movable into engagement with said interlock member on the movement of said handle to said oit position to release 'said member from interlock with said latch part and thereby condition said cover for opening movement, said handle being pivotally ymovable to oit position through said over-centering spring means without releasing said member from interlock in the eventy of said contact member being jammed in the on position.

7. An enclosure comprising a casing having an openable cover, a switch unit mounted in said casing having a contact member movable between on and olf positions, operating mechanism therefor including over-centering spring means, and an actuating handle projecting through said cover in the closed position thereof and pivotally movable to on and off positions for correspondingly actuating said contact member through said over-centering spring means, and interlocking means for said cover comprising a stationary latch part carried by said cover, and a pivotally movable interlocking member carried by said casing and releasably engageable with said latch part for latching said cover closed, said unit having a part coupled with said contact member for conjoint movement therewith and normally responsive to the movement of said handle, said part being out of engagement with said interlocking member in the on position of said handle to interlock said member with said latch part, said part being normally pivotally movable into engagement with said interlocking member on the movement of said handle to said off position to release said member from interlock with said latch part and thereby condition said cover for opening movement, said interlocking member being constituted by plural parts normally movable in unison between latching and releasing positions under the control of said unit part, said plural parts being relatively movable in one direction to provide for the movement of one of said parts to released position on the movement of said handle to oli position with the other part in latched position.

8. In combination with a switch unit having a front operated actuating handle pivotally movable to on and off positions, a casing in whichsaid unit is mounted, an openable cover for said casing, and interlocking means for said cover comprising releasably interengageable latch parts carried by said casing and cover, respectively, said casing latch part being operatively associated with said handle and normally responsive to the movement thereof whereby in the on position thereof said latch parts are interengaged to latch said cover closed, the pivotal movement of said handle to said ott position being effective to release said latch parts to condition said cover for opening movement, said casing latch part being constituted by a pivotally movable assembly comprising plural parts normally movable in unison between latching and releasing positions under the control of said handle, said plural parts being relativelymovable in one direction to provide for the movement of one of said parts to released position on the movement of said handle to oit position with the other part in latched position.

9. Enclosed switching apparatus including a switching device having an actuating handle movable to a plurality of positions, a casing in which said device is mounted, an openable cover for said casing having an opening oocupied by the switching device with the handle projecting externally thereof, and interlocking means for said cover and said handle comprising a part movable between an extended handle blocking position to prevent the movement of the handle out of position and a retracted handle releasing position, said part being in said extended posiltion with said ,cover open, and actuating means vfor said 75 2,789,169

part responsive to the position of lsaid cover whereby on the closing of said cover the latter engages said actuating means to retract said part and thereby release said handle for movement to another position.

10. Enclosed switching apparatus including a switching device having an actuating handle movable to a plurality of positions, a casing in which said `device is mounted, an openable cover for said casing having an opening occupied by the switching device with the handle projecting externally thereof, a latch for said cover movable between cover latched and cover released positions, and interlocking means for said handle comprising a part movable between an extended handle blocking position to prevent the movement of the handle out of position and a retracted handle releasing position, said part being spring-'biased against the inside of said cover whereby on the actuation of said latch to said cover released position said part projects said cover open and moves into said extended position, and actuating means for said part responsive to the position of said cover whereby on the closing of said cover the latter engages said actuating means to retract said part and thereby release said handle for movement to another position. i

1l. Enclosed switching apparatus, including detachably connected baseand cover parts secured to each other in casing Idefining relation, said base having cooperable contacts and operating mechanism therefor and said cover including an operating handle and a separable and reversible mechanical coupling to said. mechanism, i

in combination with an enclosure for saidv switching apparatus including a door having Van opening therein disposed to expose said handle and the adjoining portion of cover part, and means for preventing inadvertent operation of the handle out of its position prevailing when the door is opened regardless of which reversible position of the cover part is used, said means including a member retractably carried by said cover part and spring biased to projecting position into the path of the handle, said member having a lateral extension engaged and depressed by said door upon closing and effective to withdraw said member from the operative path of said handle.

12. Enclosed switching apparatus including an enclosure including a door having an opening therein, a switching device Within said enclosure Vand having a front operating handle and having a cover part closing said opening, said handle projecting exteriorly of said door, a door catch and a latch cooperable therewith within said enclosure, a mechanical coupling from said switching device to said latch effective to cause latching or release of said door catch successively when said switching device is closed or open, and said switching device including a door-actuated interlock forming part of said switching device and normally blocking operation of said switching device, said door-actuated interlock having a part operable by said door upon closing thereof to release vsaid switching device for operation.

13. Enclosed switching apparatus including a metal enclosure, `a front metal door having an opening therein, switching apparatus mounted in said enclosure and having a portion thereof exposed through said opening and an exposed operating handle, at least part of the exposed portions of the switching apparatus being of metal, and means for grounding said metal exposed part including a spring-biased metal member engaging said door in the closed position thereof and connected to said metal exposed part. 5

References Cited in the le of this patent UNITED STATES PATENTS 1,643,806 Davies Sept. 27, 1927 2,639,356 Savage May 19, 1953 2,646,488 Platz July 21, 1953 2,695,934 Wills Nov. 30, 1954 Duvall et al. Apr. 16, 1957 

